P1507: A PREDICTIVE MODEL OF HERPES ZOSTER AFTER ALLOGENEIC HAEMATOPOIETIC STEM CELL TRANSPLANTATION: VZV REACTIVATION AFTER ANTIVIRAL PROPHYLAXIS DISCONTINUATION
Authors: Cheng-Jie Feng, Xiao-Lu Zhu, Hai-Xia Fu, Yun He, Feng-Rong Wang, Yuan-Yuan Zhang, Xiao-Dong Mo, Chen-Hua Yan, Yuan Kong, Wei Han, Jing-Zhi Wang, Yu Wang, Huan Chen, Yu-Hong Chen, Xiang-Yu Zhao, Ying-Jun Chang, Lan-Ping Xu, Kai-Yan Liu, Xiao-Jun Huang, Xiao-Hui Zhang
Journal: HemaSphere (2023)

Topic: 30. Infections in hematology (incl. supportive care/therapy) Background: Herpes zoster (HZ) is a disease caused by varicella zoster virus reactivation. The incidence of HZ following hematopoietic stem cell transplantation (HSCT) is significantly higher than that in normal people. Apart from this consideration, patients with HZ after HSCT usually experience additional complications, such as postherpetic neuralgia (PHN), Ramsay Hunt syndrome or even disseminated herpes zoster. Although acyclovir prophylaxis is routinely performed on every patient after HSCT for 1 year, some patients eventually develop late HZ (beyond 1 year) after completing prophylaxis. However, little information is known about the incidence and risk factors for HZ after prophylactic antiviral treatment discontinuation, and an effective predictive model of late HZ must be established. Aims: The aim of this study was to explore the clinical features, risk factors and outcomes of herpes zoster patients after HSCT and to establish a predictive model of late HZ after completing antiviral prophylaxis. Methods: A total of 291 HZ patients who had completed allo-HSCT from 2012 to 2017 were identified, among whom 201 patients developed HZ after 1 year (late HZ). We performed a nested case-control study to identify the risk factors for late HZ patients (n=201), and three controls were randomly selected for each case according to the time of transplant (±1 month) and the length of follow-up (±3 months). We then established a predictive model through binary logistic regression and compared the clinical outcome of HZ patients with that of their controls. Results: The incidence of herpes zoster after HSCT was 8.7% (14.43/1000 person-years), with a median onset time of 499 days, and 69% of the HZ cases developed after one year. According to the multivariable logistic binary regression method, six highly significant independent predictive factors for late HZ were identified: age>20 (p<.001; OR, 4.22), use of immunosuppressants at +1 year (p<.001; OR, 3.98), CD4-CD8 ratio ≥4.71 at +1 year (p<.001; OR, 2.51), certain mental disorders (p<.001; OR, 5.58), engraftment time of granulocytes > 15 days (p<.001; OR, 2.78), and CD8+ cell count ≥77.4/µl at +30 days (p<.001; OR, 0.097). A risk grading model termed the AIRMET score (age, immunosuppressant, CD4-CD8 ratio, mental disorder, engraftment time, and CD8+ T cells) was constructed according to the regression coefficients. The validated c-statistic was 0.813. According to the calibration plots, the model-predicted probabilities showed a good correlation with actual observed frequencies. A decision curve analysis indicated that the clinical implementation of this model could benefit HZ patients. The survival rate of patients with HZ was lower than that of the control group, and the GVHD-relapse-free survival (GRFS) rate was significantly lower than that of the control group (p<.001). Among all the patients with post-HSCT herpes zoster, the incidence of zoster complications was 9%, and PHN was the most common complication. We found that age ≥25 (p=.016; OR, 2.78) and grade II~IV aGVHD (p=.043; OR, 2.06) were risk factors for HZ complications. The decision to continue antiviral prophylaxis at 1 year was positively correlated with the use of immunosuppressant treatment during the same period in our centre, which may delay the onset time of HZ. Summary/Conclusion: Patients who develop HZ after HSCT have poor quality of life. A predictive model (AIRMET) was developed and validated, and this is the first scoring system predicting the incidence of late HZ after allo-HSCT. This model can be applied to improve the long-term life quality of HSCT patients by accelerating the early identification of patients at high risk of HZ. Keywords: Allo-SCT, Infection, Herpesvirus, Prophylaxis